Background The association between cancer and stroke or bleeding outcomes in atrial fibrillation is unclear. We sought to examine how certain types of cancer influence the balance between stroke and bleeding risk in patients with nonvalvular atrial fibrillation (NVAF). Methods and Results We estimated stroke and bleeding risk among adult patients with NVAF and certain types of cancer (breast, prostate, colorectal, lung, and hematological cancer) from 2009 to 2019 based on data from the UK Clinical Practice Research Datalink GOLD and Aurum databases. The control group included patients with NVAF only. Of 177 065 patients with NVAF, 11379 (6.4%) had cancer (1691 breast, 3955 prostate, 1666 colorectal, 2491 hematological, and 1576 lung). Compared with patients without cancer, stroke risk was higher in patients with breast cancer (adjusted hazard ratio [aHR], 1.20 [95% CI, 1.07–1.35) and with prostate cancer (aHR, 1.11 [95% CI, 1.01–1.12) if diagnosed within 6 months before NVAF. The risk of bleeding was increased in subjects with hematological cancer (aHR, 1.55 [95% CI, 1.40–1.71]), lung cancer (aHR, 1.49 [95% CI, 1.25, 1.77]), prostate cancer (aHR, 1.38 [95% CI, 1.28–1.49]), and colorectal cancer (aHR, 1.36 [95% CI, 1.21–1.53]), but not for subjects with breast cancer. The more recent the cancer diagnosis before NVAF diagnosis (within 6 months), the higher the risk of bleeding. Conclusions Breast and prostate cancer are associated with increased stroke risk, whereas in some cancer types, the risk of bleeding seemed to exceed stroke risk. In these patients, prescribing of oral anticoagulant should be carefully evaluated to balance bleeding and stroke risk.